63

piers are 155 feet high and 27 feet wide,

— = _L

155 577

In the bridge near Terni , the bearingpiers are 108 feet high and 27 feet wide,27 _ 1

108 ~i

In the aqueduct of Spoletto the bear-ing piers are 260 feet high and 11.7•j 11 -7 1

Wlde ’ iso = ii

The above piers are in section parallelo-grams.

In the aqueduct at Lisbon , the bearingpiers batter; their height is 150 feet, their

25 1

width at bottom 25 feet, then — = the

difference in width between the bottomsand tops of these piers is not much. (SeeGauthey, des Ponts.)

1st. It appears manifest that there is nodanger of the stone being crushed if thepier be wider than five feet at the top, andin a bearing pier the horizontal draft is sup-posed nothing ; therefore that would be asufficient width to prevent the stone beingcrushed, supposing it of no height, by cal-culation.